A gene analysis is useful in the fields of molecular biology and biochemistry, and employed recently also in a medical field, for example, to identify a disease.
Recently, a substrate on which a DNA had been immobilized was developed, and served to enable a substantial promotion of a gene analysis, which is applied also to the diagnosis of a disease in the medical field.
As a method for immobilizing a DNA on a substrate, a method was proposed wherein a polymer such as a polylysine is applied onto the surface of a glass slide or silicon substrate prior to the immobilization or wherein a semiconductor technology such as a photolithography is employed to synthesize a DNA on a substrate.
However, the method for immobilizing a DNA by applying a polymer such as a polylysine involves a problem due to the detachment of the DNA during a hybrid formation step and a washing step due to an unstable immobilization state of the DNA.
On the other hand, the method utilizing the semiconductor technology involves a problematically complicated manufacturing process which leads to an extremely high cost.
For the purpose of solving the problems mentioned above, we had already found that by modifying a substrate surface chemically to effect an activation by an active ester such as N-hydroxysuccinimide ester or p-nitrophenol ester a DNA can stably be immobilized.
Nevertheless, such a chemical modification requires a complicated procedure involving a large number of chemical reactions.
In addition, an activated substrate obtained by a chemical modification may allow any unwanted active points to be still remaining as they are even after spotting a DNA on the substrate.
Accordingly, such an unwanted active point, upon hybridizing a target DNA to the spotted DNA, allows the DNA to deposit also to itself, resulting in a problematic difficulty in detecting the DNA accurately.
Thus, an objective of the invention is to provide a method for immobilizing a DNA on a substrate in a simple manner but firmly at a high density as experienced in a conventional method and also a method for detecting a DNA and the like accurately, whereby overcoming the problems associated with conventional DNA immobilization methods described above.